In a cooling fan for a blower unit, it is proposed to provide a ring member on an outer periphery of fan blades that extend in a radial direction from a cylindrical boss portion. In a propeller fan disclosed in Japanese Utility Application Publication No. JP-U-62-152098, a ring portion is integrally formed with a plurality of blades as an air guide such that the ring portion extends linearly and is in contact with radial outside edges of the blades. The fan does not form a gap between the ring portion and the radial outside edges of the blades, thereby to reduce fan noise. Further, the ring portion forms an extending portion in a form of bell to improve air blowing efficiency and reduce the noise. However, a detailed position of the extending portion with respect to the blades is not suggested in JP-U-62-152098.